Enable HTTP loading in Mojo dart content handler

mojo/dart/http_load_test/tester.dart

Index: mojo/dart/http_load_test/tester.dart
diff --git a/mojo/dart/http_load_test/tester.dart b/mojo/dart/http_load_test/tester.dart
new file mode 100644
index 0000000000000000000000000000000000000000..70eb61bc1fb285a826f3cf59a4a3df697ae334e2
--- /dev/null
+++ b/mojo/dart/http_load_test/tester.dart
@@ -0,0 +1,70 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+library http_load_test;
+
+import 'dart:async';
+import 'dart:convert';
+import 'dart:io';
+
+class Launcher {
+  /// Launch [executable] with [arguments]. Returns a [String] containing
+  /// the standard output from the launched executable.
+  static Future<String> launch(String executable,
+                               List<String> arguments) async {
+    var process = await Process.start(executable, arguments);
+
+    // Completer completes once the child process exits.
+    var completer = new Completer();
+    String stdout = '';
+    process.stdout.transform(UTF8.decoder)
+                  .transform(new LineSplitter()).listen((line) {
+      stdout = '$stdout\n$line';
+      print(line);
+    });
+    process.stderr.transform(UTF8.decoder)
+                  .transform(new LineSplitter()).listen((line) {
+      print(line);
+    });
+    process.exitCode.then((ec) {
+      stdout = '$stdout\nEXIT_CODE=$ec\n';
+      completer.complete(stdout);
+    });
+    return completer.future;
+  }
+}
+
+main(List<String> args) async {
+  var mojo_shell_executable = args[0];
+  var directory = args[1];
+
+  HttpServer server = await HttpServer.bind('127.0.0.1', 0);
+
+  server.listen((HttpRequest request) async {
+    final String path = request.uri.toFilePath();
+    final File file = new File('${directory}/${path}');
+    if (await file.exists()) {
+      try {
+        await file.openRead().pipe(request.response);
+      } catch (e) {
+        print(e);
+      }
+    } else {
+      request.response.statusCode = HttpStatus.NOT_FOUND;
+      request.response.close();
+    }
+  });
+
+  var launchUrl = 'http://127.0.0.1:${server.port}/main.dart';
+  var stdout = await Launcher.launch(mojo_shell_executable, [launchUrl]);
+
+  server.close();
+
+  if (!stdout.contains("\nPASS")) {
+    throw "Test failed.";
+  }
+  if (!stdout.contains("\nEXIT_CODE=0\n")) {
+    throw "Test failed.";
+  }
+}